The proposed study is a randomized controlled trial of AIM HI, an intervention designed specifically for implementation in community mental health clinics, to reduce problem behavior among school-age children with autism spectrum disorders (ASD). The CMH system plays an important role in caring for school-age children with ASD, especially those who exhibit challenging behaviors. Unfortunately, there are widespread concerns about the quality of care provided to children with ASD in CMH services as therapists lack specialized training to address the complex needs of children with ASD, particularly behavior problems, and do not use EBPs consistently or intensively. Targeting the most common presenting problems has potential to make a significant impact on care for most children with ASD served in CMH clinics. Implementing existing EBPs for ASD in CMH clinics offers an innovative solution to the quality gap in CMH service settings. Our pilot data indicate that clinics and providers are eager to learn how to effectively treat children with ASD. However, existing EBPs were not designed for delivery within CMH clinics. Our previous research began to address the lack of readily implementable EBPs to treat behavior problems in children with ASD. Specifically, we identified and packaged EBP strategies based on the clinical needs of children and training needs of therapists, resulting in the final intervention protocol, An Individualized Mental Health Intervention for Children with ASD (AIM HI). AIM HI is a package of EBP strategies, based on the principles of applied behavior analysis, designed to reduce challenging behaviors in children with ASD ages 5 to 13 served in CMH clinics. Although the individual components of AIM HI are well-established EBP strategies and pilot study data indicate that child behavior problems decrease when their CMH therapists deliver AIM HI, the effectiveness of the protocol has not been established. Therefore, the primary aims are to test the impact of AIM HI on child and family outcomes and determine how child/ family characteristics and level of therapist fidelity moderate treatment effects. Our secondary aim is to collect initial data on implementation outcomes and conduct exploratory analyses to identify barriers and facilitators of AIM HI implementation (e.g., intervention, organization, provider characteristics). Participants will include 29 clinics recruited from San Diego County's publicly-funded service system, 39 program managers, 223 therapists, and 301 child/ parent dyads. The study builds directly on the promising results from the PI's career development award. Our previous studies in this service system provide the empirical, methodological, and collaborative foundation to support the adoption and implementation of the intervention. It also supports the feasibility and validity of the research methods to assess the intervention's fidelity and effectiveness. Consistent with the IACC Strategic Plan for ASD research and Objective 4 of NIMH's Strategic Plan, testing the effectiveness of packages of EBP strategies in usual care settings is hypothesized to ultimately improve treatment of children with ASD in the community.